Siemens SIMATIC S5 1P 243, Инструкция по эксплуатации и установке

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In addition, a critical insulation resistance is specified for the stator winding, which is the
minimum requirement for further operation, e.g. following longer machine downtimes.
Table 7-1 Stator winding insulation resistance at 40° C
U
rated
[V]
U
meas
[V]
R
C
[MΩ]
R
C, operation
[MΩ]
R
T
[MΩ]
PI
U ≤ 1000 500 ≥ 5 0.2 MΩ/kV
(≈0.5 MΩ/kV at 25° C)
5
7
5
&
7
> 2,0
1000 ≤ U ≤ 2500 500 (max. 1000) 100 1.8 MΩ/kV
(≈5 MΩ/kV at 25° C) 2500 < U ≤ 5000 1000 (max. 2500)
5000 < U ≤ 12000 2500 (max. 5000)
U > 12000 5000 (max. 10000)
U
rated
= rated voltage, see the rating plate
U
meas
= DC measuring voltage
R
C
= critical or minimum insulation resistance at reference temperature of 40° C
R
C
= minimum insulation resistance after cleaning/repair at 40° C
R
C, operation
= critical insulation resistance during operation at 40° C
R
T
= insulation resistance converted to current measuring/winding temperature
PI = polarization index R
insul 10 min
/ R
insul 1 min.
(T ≤ 40° C)
T = current measuring/winding temperature
Note the following:
● When making measurements at winding temperatures other than 40 °C, the measured
value must be converted to the reference temperature of 40 °C. The conversion is made
using the formula from IEEE 43‑2000 specified in the table. In so doing, doubling or halving
the insulation resistance for a temperature change of 10 K is used as basis.
– The insulation resistance halves every time the temperature rises by 10 K.
– The resistance doubles every time the temperature falls by 10 K.
● Dry, new windings have insulation resistance of between 100 and 2000 MΩ, or possibly
even higher values. Insulation resistance close to the minimum value could be due to
humidity and/or dirt accumulation. However, the size of the winding, the rated voltage and
other characteristics affect the insulation resistance and may need to be taken into account
when determining measures.
● Over its operating lifetime, the motor winding insulation resistance can drop due to ambient
and operational influences. Depending on the rated voltage, the critical insulation resistance
value is to be calculated by multiplying the rated voltage (kV) by the specific critical
resistance value and then converted to the current winding temperature at the time of the
measurement, see previous table.
Example calculation
Critical resistance for a rated voltage (V
N
) of 3.3 kV:
3.3 kV x 1.8 MΩ / kV = 6 MΩ at 40 °C
Commissioning
7.3 Testing the insulation resistance and polarization index
LOHER CHEMSTAR 1PS5
Operating Instructions 03/2014
71